8 .ds RF FORMFEED[Page %]
12 .ds CH Secure Internet Live Conferencing
17 Network Working Group P. Riikonen
19 draft-riikonen-silc-spec-00.txt 28 June 2000
25 Secure Internet Live Conferencing (SILC),
26 Protocol Specification
31 This document is an Internet-Draft. Internet-Drafts are working
32 documents of the Internet Engineering Task Force (IETF), its areas,
33 and its working groups. Note that other groups may also distribute
34 working documents as Internet-Drafts.
36 Internet-Drafts are draft documents valid for a maximum of six
37 months and may be updated, replaced, or obsoleted by other
38 documents at any time. It is inappropriate to use Internet-Drafts
39 as reference material or to cite them other than as
42 To learn the current status of any Internet-Draft, please check the
43 ``1id-abstracts.txt'' listing contained in the Internet-Drafts
44 Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),
45 munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or
46 ftp.isi.edu (US West Coast).
48 The distribution of this memo is unlimited.
54 This memo describes a Secure Internet Live Conferencing (SILC)
55 protocol which provides secure conferencing services over insecure
56 network channel. SILC is IRC [IRC] like protocol, however, it is
57 not equivalent to IRC and does not support IRC. Strong cryptographic
58 methods are used to protect SILC packets inside SILC network. Two
59 other Internet Drafts relates very closely to this memo; SILC Packet
60 Protocol [SILC2] and SILC Key Exchange and Authentication Protocols
74 1 Introduction .................................................. 3
75 2 SILC Concepts ................................................. 3
76 2.1 SILC Network Topology ..................................... 4
77 2.2 Communication Inside a Cell ............................... 5
78 2.3 Communication in the Network .............................. 6
79 2.4 Channel Communication ..................................... 7
80 3 SILC Specification ............................................ 7
81 3.1 Client .................................................... 7
82 3.1.1 Client ID ........................................... 8
83 3.2 Server .................................................... 8
84 3.2.1 Server's Local ID List .............................. 9
85 3.2.2 Server ID ........................................... 10
86 3.2.3 SILC Server Ports ................................... 10
87 3.3 Router .................................................... 11
88 3.3.1 Router's Local ID List .............................. 11
89 3.3.2 Router's Global ID List ............................. 12
90 3.3.3 Router's Server ID .................................. 12
91 3.4 Channels .................................................. 12
92 3.4.1 Channel ID .......................................... 13
93 3.5 Operators ................................................. 14
94 3.6 SILC Commands ............................................. 14
95 3.7 SILC Packets .............................................. 15
96 3.8 Packet Encryption ......................................... 15
97 3.8.1 Determination of the Source and the Destination ..... 16
98 3.8.2 Client To Client .................................... 16
99 3.8.3 Client To Channel ................................... 17
100 3.8.4 Server To Server .................................... 18
101 3.9 Key Exchange And Authentication ........................... 18
102 3.10 Algorithms ............................................... 19
103 3.10.1 Ciphers ............................................ 19
104 3.10.2 Public Key Algorithms .............................. 20
105 3.10.3 MAC Algorithms ..................................... 20
106 3.10.4 Compression Algorithms ............................. 20
107 3.11 SILC Public Key .......................................... 21
108 4 SILC Procedures ............................................... 23
109 4.1 Creating Client Connection ................................ 23
110 4.2 Creating Server Connection ................................ 24
111 4.3 Joining to a Channel ...................................... 25
112 4.4 Channel Key Generation .................................... 26
113 4.5 Private Message Sending and Reception ..................... 27
114 4.6 Private Message Key Generation ............................ 27
115 4.7 Channel Message Sending and Reception ..................... 28
116 4.8 Session Key Regeneration .................................. 28
117 4.9 Command Sending and Reception ............................. 29
118 5 SILC Commands ................................................. 29
119 5.1 SILC Commands Syntax ...................................... 29
120 5.2 SILC Commands List ........................................ 31
121 5.3 SILC Command Status Types ................................. 54
122 5.3.1 SILC Command Status Payload ......................... 54
123 5.3.2 SILC Command Status List ............................ 54
124 6 Security Considerations ....................................... 58
125 7 References .................................................... 59
126 8 Author's Address .............................................. 60
133 Figure 1: SILC Network Topology
134 Figure 2: Communication Inside cell
135 Figure 3: Communication Between Cells
136 Figure 4: SILC Public Key
137 Figure 5: SILC Command Status Payload
143 This document describes a Secure Internet Live Conferencing (SILC)
144 protocol which provides secure conferencing services over insecure
145 network channel. SILC is IRC [IRC] like protocol, however, it is
146 not equivalent to IRC and does not support IRC. Strong cryptographic
147 methods are used to protect SILC packets inside SILC network. Two
148 other Internet Drafts relates very closely to this memo; SILC Packet
149 Protocol [SILC2] and SILC Key Exchange and Authentication Protocols
152 The protocol uses extensively packets as conferencing protocol
153 requires message and command sending. The SILC Packet Protocol is
154 described in [SILC2] and should be read to fully comprehend this
155 document and protocol. [SILC2] also describes the packet encryption
156 and decryption in detail.
158 The security of SILC protocol and for any security protocol for that
159 matter is based on strong and secure key exchange protocol. The SILC
160 Key Exchange protocol is described in [SILC3] along with connection
161 authentication protocol and should be read to fully comprehend this
162 document and protocol.
164 The SILC protocol has been developed to work on TCP/IP network
165 protocol, although it could be made to work on other network protocols
166 with only minor changes. However, it is recommended that TCP/IP
167 protocol is used under SILC protocol. Typical implementation would
168 be made in client-server model.
174 This section describes various SILC protocol concepts that forms the
175 actual protocol, and in the end, the actual SILC network. The mission
176 of the protocol is to deliver messages from clients to other clients
177 through routers and servers in secure manner. The messages may also
178 be delivered from one client to many clients forming a group, also
181 This section does not focus to security issues, instead basic network
182 concepts are introduced to make the topology of the SILC network
187 2.1 SILC Network Topology
189 SILC network is a cellular network as opposed to tree style network
190 topology. The rationale for this is to have servers that can perform
191 specific kind of tasks what other servers cannot perform. This leads
192 to two kinds of servers; normal SILC servers and SILC routers.
193 A difference between normal server and router server is that routers
194 knows everything about everything in the network. They also do the
195 actual routing of the messages to the correct receiver. Normal servers
196 knows only about local information and nothing about global information.
197 This makes the network faster as there are less servers that needs to
198 keep global information up to date at all time.
200 This, on the other hand, leads to cellular like network, where routers
201 are in the centrum on the cell and servers are connected to the router.
202 Following diagram represents SILC network topology.
207 ---- ---- ---- ---- ---- ----
208 | S8 | S5 | S4 | | S7 | S5 | S6 |
209 ----- ---- ----- ----- ---- -----
210 | S7 | S/R1 | S2 | --- | S8 | S/R2 | S4 |
211 ---- ------ ---- ---- ------ ----
212 | S6 | S3 | S1 | | S1 | S3 | S2 | ---- ----
213 ---- ---- ---- ---- ---- ---- | S3 | S1 |
214 Cell 1. \\ Cell 2. | \\____ ----- -----
216 ---- ---- ---- ---- ---- ---- ---- ------
217 | S7 | S4 | S2 | | S1 | S3 | S2 | | S2 | S5 |
218 ----- ---- ----- ----- ---- ----- ---- ----
219 | S6 | S/R3 | S1 | --- | S4 | S/R5 | S5 | Cell 4.
220 ---- ------ ---- ---- ------ ----
221 | S8 | S5 | S3 | | S6 | S7 | S8 | ... etc ...
222 ---- ---- ---- ---- ---- ----
227 Figure 1: SILC Network Topology
230 A cell is formed when a server or servers connect to one router. In
231 SILC network normal server cannot directly connect to other normal
232 server. Normal server may only connect to SILC router which then
233 routes the messages to the other servers in the cell. Router servers
234 on the other hand may connect to other routers to form the actual SILC
235 network, as seen in above figure. However, router is also normal SILC
236 server; clients may connect to it the same way as to normal SILC
237 servers. Normal server also cannot have active connections to more
238 than one router. Normal server cannot be connected to two different
239 cells. Router servers, on the other hand, may have as many router to
240 router connections as needed.
242 There are many issues in this network topology that needs to be careful
243 about. Issues like the size of the cells, the number of the routers in
244 the SILC network and the capacity requirements of the routers. These
245 issues should be discussed in the Internet Community and additional
246 documents on the issue will be written.
250 2.2 Communication Inside a Cell
252 It is always guaranteed that inside a cell message is delivered to the
253 recipient with at most two server hops. Client who is connected to
254 server in the cell and is talking on channel to other client connected
255 to other server in the same cell, will have its messages delivered from
256 its local server first to the router of the cell, and from the router
257 to the other server in the cell. Following diagram represents this
272 Figure 2: Communication Inside cell
275 Example: Client 1. connected to Server 1. message sent to
276 Client 4. connected to Server 2. travels from Server 1.
277 first to Router which routes the message to Server 2.
278 which then sends it to the Client 4. All the other
279 servers in the cell will not see the routed message.
282 If client is connected directly to the router, as router is also normal
283 SILC server, the messages inside the cell are always delivered only with
284 one server hop. If clients communicating with each other are connected
285 to the same server, no router interaction is needed. This is the optimal
286 situation of message delivery in the SILC network.
290 2.3 Communication in the Network
292 If the message is destined to server that does not belong to local cell
293 the message is routed to the router server to which the destination
294 server belongs, if the local router is connected to destination router.
295 If there is no direct connection to the destination router, the local
296 router routes the message to its primary route. Following diagram
297 represents message sending between cells.
302 1 --- S1 S4 --- 5 S2 --- 1
303 S/R - - - - - - - - S/R
313 Figure 3: Communication Between Cells
316 Example: Client 5. connected to Server 4. in Cell 1. message sent
317 to Client 2. connected to Server 1. in Cell 2. travels
318 from Server 4. to Router which routes the message to
319 Router in Cell 2, which then routes the message to
320 Server 1. All the other servers and routers in the
321 network will not see the routed message.
324 The optimal case of message delivery from client point of view is
325 when clients are connected directly to the routers and the messages
326 are delivered from one router to the other router.
333 2.4 Channel Communication
335 Messages may be sent to group of clients as well. Sending messages to
336 many clients works the same way as sending messages point to point, from
337 message delivery point of view. Security issues are another matter
338 which are not discussed in this section.
340 Router server handles the message routing to multiple recipients. If
341 any recipient is not in the same cell as the sender the messages are
344 Server distributes the channel message to its local clients who are
345 joined to the channel. Also, router distributes the message to its
346 local clients on the channel.
350 3. SILC Specification
352 This section describes the SILC protocol. However, [SILC2] and
353 [SILC3] describes other important protocols that are part of this SILC
354 specification and must be read.
360 A client is a piece of software connecting to SILC server. SILC client
361 cannot be SILC server. Purpose of clients is to provide the user
362 interface of the SILC services for end user. Clients are distinguished
363 from other clients by unique Client ID. Client ID is a 128 bit ID that
364 is used in the communication in the SILC network. The client ID is
365 based on the nickname selected by the user. User uses logical nicknames
366 in communication which are then mapped to the corresponding Client ID.
367 Client ID's are low level identifications and must not be seen by the
370 Clients provide other information about the end user as well. Information
371 such as the nickname of the user, username and the hostname of the end
372 user and user's real name. See section 3.2 Server for information of
373 the requirements of keeping this information.
375 The nickname selected by the user is not unique in the SILC network.
376 There can be 2^8 same nicknames for one IP address. As for comparison to
377 IRC [IRC] where nicknames are unique this is a fundamental difference
378 between SILC and IRC. This causes the server names to be used along
379 with the nicknames to identify specific users when sending messages.
380 This feature of SILC makes IRC style nickname-wars obsolete as no one
381 owns their nickname; there can always be someone else with the same
382 nickname. Another difference is that there are no limit of the length
383 of the nickname in the SILC.
389 Client ID is used to identify users in the SILC network. The Client ID
390 is unique to the extent that there can be 2^128 different Client ID's.
391 Collisions are not expected to happen. The Client ID is defined as
395 128 bit Client ID based on IPv4 addresses:
397 32 bit ServerID IP address (bits 1-32)
399 88 bit Truncated MD5 hash value of the nickname
401 o Server ID IP address - Indicates the server where this
402 client is coming from. The IP address hence equals the
403 server IP address where to the client has connected.
405 o Random number - Random number to further unify the
406 Client ID. This makes it possible to have 2^8 same
407 nicknames from the same server IP address.
409 o MD5 hash - MD5 hash value of the nickname is truncated
410 taking 88 bits from the start of the hash value. This
411 hash value is used to search the user's Client ID from
415 Collisions could occur when more than 2^8 clients using same nickname
416 from the same server IP address is connected to the SILC network.
417 Server must be able to handle this situation by refusing to accept
418 anymore of that nickname.
420 Another possible collision may happen with the truncated hash value of
421 the nickname. It could be possible to have same truncated hash value for
422 two different nicknames. However, this is not expected to happen nor
423 cause any problems if it would occur. Nicknames are usually logical and
424 it is unlikely to have two distinct logical nicknames produce same
425 truncated hash value.
431 Servers are the most important parts of the SILC network. They form the
432 basis of the SILC, providing a point to which clients may connect to.
433 There are two kinds of servers in SILC; normal servers and router servers.
434 This section focuses on the normal server and router server is described
435 in the section 3.3 Router.
437 Normal servers may not directly connect to other normal server. Normal
438 servers may only directly connect to router server. If the message sent
439 by the client is destined outside the local server it is always sent to
440 the router server for further routing. Server may only have one active
441 connection to router on same port. Normal server may not connect to other
442 cell's router except in situations where its cell's router is unavailable.
444 Servers and routers in the SILC network are considered to be trusted.
445 With out a doubt, servers that are set to work on ports above 1023 are
446 not considered to be trusted. Also, the service provider acts important
447 role in the server's trustworthy.
451 3.2.1 Server's Local ID List
453 Normal server keeps various information about the clients and their end
454 users connected to it. Every normal server must keep list of all locally
455 connected clients, Client ID's, nicknames, usernames and hostnames and
456 user's real name. Normal servers only keeps local information and it
457 does not keep any global information. Hence, normal servers knows only
458 about their locally connected clients. This makes servers efficient as
459 they don't have to worry about global clients. Server is also responsible
460 of creating the Client ID's for their clients.
462 Normal server also keeps information about locally created channels and
465 Hence, local list for normal server includes:
468 server list - Router connection
476 client list - All clients in server
486 channel list - All channels in server
489 o Client ID's on channel
490 o Client ID modes on channel
499 Servers are distinguished from other servers by unique 64 bit Server ID.
500 The Server ID is used in the SILC to route messages to correct servers.
501 Server ID's also provide information for Client ID's, see section 3.1.1
502 Client ID. Server ID is defined as follows.
505 64 bit Server ID based on IPv4 addresses:
507 32 bit IP address of the server
511 o IP address of the server - This is the real IP address of
514 o Port - This is the port the server is binded to.
516 o Random number - This is used to further unify the Server ID.
519 Collisions are not expected to happen in any conditions. The Server ID
520 is always created by the server itself and server is resposible of
521 distributing it to the router.
525 3.2.3 SILC Server Ports
527 SILC uses currently TCP port 334 on SILC network. However, this is not
528 official port assigned for SILC. Official port has been requested by
531 If there are needs to create new SILC networks in the future the port
532 numbers must be officially assigned by the IANA. Most convenience case
533 would be to assign port numbers upwards from 334.
535 Server on network above privileged ports (>1023) should not be trusted
536 as they could have been set up by untrusted party.
542 Router server in SILC network is responsible for keeping the cell together
543 and routing messages to other servers and to other routers. Router server
544 is also a normal server thus clients may connect to it as it would be
545 just normal SILC server.
547 However, router servers has a lot of important tasks that normal servers
548 do not have. Router server knows everything about everything in the SILC.
549 They know all clients currently on SILC, all servers and routers and all
550 channels in SILC. Routers are the only servers in SILC that care about
551 global information and keeping them up to date at all time. And, this
552 is what they must do.
556 3.3.1 Router's Local ID List
558 Router server as well must keep local list of connected clients and
559 locally created channels. However, this list is extended to include all
560 the informations of the entire cell, not just the server itself as for
563 However, on router this list is a lot smaller since routers do not keep
564 information about user's nickname, username and hostname and real name
565 since these are not needed by the router. Router keeps only information
568 Hence, local list for router includes:
571 server list - All servers in the cell
578 client list - All clients in the cell
581 channel list - All channels in the cell
583 o Client ID's on channel
584 o Client ID modes on channel
589 Note that locally connected clients and other information include all the
590 same information as defined in section section 3.2.1 Server's Local ID
595 3.3.2 Router's Global ID List
597 Router server must also keep global list. Normal servers do not have
598 global list as they know only about local information. Global list
599 includes all the clients on SILC, their Client ID's, all created channels
600 and their Channel ID's and all servers and routers on SILC and their
601 Server ID's. That is said, global list is for global information and the
602 list must not include the local information already on the router's local
605 Note that the global list does not include information like nicknames,
606 usernames and hostnames or user's real names. Router does not keep
607 these informations as they are not needed by the router. This
608 information is available from the client's server which maybe queried
611 Hence, global list includes:
614 server list - All servers in SILC
619 client list - All clients in SILC
622 channel list - All channels in SILC
624 o Client ID's on channel
625 o Client ID modes on channel
630 3.3.3 Router's Server ID
632 Router's Server ID's are equivalent to normal Server ID's. As routers
633 are normal servers as well same types of ID's applies for routers as well.
634 Thus, see section 3.2.2 Server ID. Server ID's for routers are always
635 created by the remote router where the router is connected to.
641 A channel is a named group of one or more clients which will all receive
642 messages addressed to that channel. The channel is created when first
643 client requests JOIN command to the channel, and the channel ceases to
644 exist when the last client leaves it. When channel exists, any client
645 can reference it using the name of the channel.
647 Channel names are unique although the real uniqueness comes from 64 bit
648 Channel ID that unifies each channel. However, channel names are still
649 unique and no two global channels with same name may exist. Channel name
650 is a string which begins with `#' character. There is no limit on the
651 length of the channel name. Channel names may not contain any spaces
652 (` '), any non-printable ASCII characters, commas (`,') and wildcard
655 Channels can have operators that can administrate the channel and
656 operate all of its modes. Following operators on channel exist on SILC
660 o Channel founder - When channel is created the joining client becomes
661 channel founder. Channel founder is channel operator with some more
662 privileges. Basically, channel founder can fully operate the channel
663 and all of its modes. The privileges are limited only to the particular
664 channel. There can be only one channel founder per channel. Channel
665 founder supersedes channel operator's privileges.
667 Channel founder privileges cannot be removed by any other operator on
668 channel. When channel founder leaves the channel there is no channel
669 founder on the channel. Channel founder also cannot be removed by
670 force from the channel.
672 o Channel operator - When client joins to channel that has not existed
673 previously it will become automatically channel operator (and channel
674 founder discussed above). Channel operator is able administrate the
675 channel, set some modes on channel, remove a badly behaving client from
676 the channel and promote other clients to become channel operator.
677 The privileges are limited only to the particular channel.
679 Normal channel user may be promoted (opped) to channel operator
680 gaining channel operator privileges. Channel founder or other channel
681 operator may also demote (deop) channel operator to normal channel
689 Channels are distinguished from other channels by unique Channel ID.
690 The Channel ID is a 64 bit ID and collisions are not expected to happen
691 in any conditions. Channel names are just for logical use of channels.
692 The Channel ID is created by the server where the channel is created.
693 The Channel ID is defined as follows.
696 64 bit Channel ID based on IPv4 addresses:
698 32 bit Router's Server ID IP address (bits 1-32)
699 16 bit Router's Server ID port (bits 33-48)
702 o Router's Server ID IP address - Indicates the IP address of
703 the router of the cell where this channel is created. This is
704 taken from the router's Server ID. This way SILC router knows
705 where this channel resides in the SILC network.
707 o Router's Server ID port - Indicates the port of the channel on
708 the server. This is taken from the router's Server ID.
710 o Random number - To further unify the Channel ID. This makes
711 sure that there are no collisions. This also means that
712 in a cell there can be 2^16 channels.
719 Operators are normal users with extra privileges to their server or
720 router. Usually these people are SILC server and router administrators
721 that take care of their own server and clients on them. The purpose of
722 operators is to administrate the SILC server or router. However, even
723 an operator with highest privileges is not able to enter invite-only
724 channel, to gain access to the contents of a encrypted and authenticated
725 packets traveling in the SILC network or to gain channel operator
726 privileges on public channels without being promoted. They have the
727 same privileges as everyone else except they are able to administrate
728 their server or router.
734 Commands are very important part on SILC network especially for client
735 which uses commands to operate on the SILC network. Commands are used
736 to set nickname, join to channel, change modes and many other things.
738 Client usually sends the commands and server replies by sending a reply
739 packet to the command. Server may also send commands usually to serve
740 the original client's request. However, server may not send command
741 to client and there are some commands that server must not send.
743 Note that the command reply is usually sent only after client has sent
744 the command request but server is allowed to send command reply packet
745 to client even if client has not requested the command. Client may,
746 however, choose not to accept the command reply, but there are some
747 command replies that the client should accept. Example of a such
748 command reply is reply to SILC_COMMAND_CMODE command that the server
749 uses to distribute the channel mode on all clients on the channel
750 when the mode has changed.
752 It is expected that some of the commands may be miss-used by clients
753 resulting various problems on the server side. Every implementation
754 should assure that commands may not be executed more than once, say,
755 in two (2) seconds. This should be sufficient to prevent the miss-use
758 SILC commands are described in section 5 SILC Commands.
764 Packets are naturally the most important part of the protocol and the
765 packets are what actually makes the protocol. Packets in SILC network
766 are always encrypted using, usually, the shared secret session key
767 or some other key, for example, channel key, when encrypting channel
768 messages. The SILC Packet Protocol is a wide protocol and is described
769 in [SILC2]. This document does not define or describe details of
774 3.8 Packet Encryption
776 All packets passed in SILC network must be encrypted. This section
777 defines how packets must be encrypted in the SILC network. The detailed
778 description of the actual encryption process of the packets are
779 described in [SILC2].
781 Client and its server shares secret symmetric session key which is
782 established by the SILC Key Exchange Protocol, described in [SILC3].
783 Every packet sent from client to server, with exception of packets for
784 channels, are encrypted with this session key.
786 Channels has their own key that are shared by every client on the channel.
787 However, the channel keys are cell specific thus one cell does not know
788 the channel key of the other cell, even if that key is for same channel.
789 Channel key is also known by the routers and all servers that has clients
790 on the channel. However, channels may have channel private keys that
791 are entirely local setting for client. All clients on the channel must
792 know the channel private key before hand to be able to talk on the
793 channel. In this case, no server or router knows the key for channel.
795 Server shares secret symmetric session key with router which is
796 established by the SILC Key Exchange Protocol. Every packet passed from
797 server to router, with exception of packets for channels, are encrypted
798 with the shared session key. Same way, router server shares secret
799 symmetric key with its primary route. However, every packet passed
800 from router to other router, including packets for channels, are
801 encrypted with the shared session key. Every router connection has
802 their own session keys.
806 3.8.1 Determination of the Source and the Destination
808 The source and the destination of the packet needs to be determined
809 to be able to route the packets to correct receiver. This information
810 is available in the SILC Packet Header which is included in all packets
811 sent in SILC network. The SILC Packet Header is described in [SILC2].
813 The header is always encrypted with the session key who is next receiver
814 of the packet along the route. The receiver of the packet, for example
815 a router along the route, is able to determine the sender and the
816 destination of the packet by decrypting the SILC Packet Header and
817 checking the ID's attached to the header. The ID's in the header will
818 tell to where the packet needs to be sent and where it is coming from.
820 The header in the packet does not change during the routing of the
821 packet. The original sender, for example client, assembles the packet
822 and the packet header and server or router between the sender and the
823 receiver must not change the packet header.
825 Note that the packet and the packet header may be encrypted with
826 different keys. For example, packets to channels are encrypted with
827 the channel key, however, the header is encrypted with the session key
828 as described above. However, the header and the packet may be encrypted
829 with same key. This is case, for example, with command packets.
833 3.8.2 Client To Client
835 Process of message delivery and encryption from client to another
836 client is as follows.
838 Example: Private message from client to another client on different
839 servers. Clients do not share private message delivery
840 keys; normal session keys are used.
842 o Client 1. sends encrypted packet to its server. The packet is
843 encrypted with the session key shared between client and its
846 o Server determines the destination of the packet and decrypts
847 the packet. Server encrypts the packet with session key shared
848 between the server and its router, and sends the packet to the
851 o Router determines the destination of the packet and decrypts
852 the packet. Router encrypts the packet with session key
853 shared between the router and the destination server, and sends
854 the packet to the server.
856 o Server determines the client to which the packet is destined
857 to and decrypts the packet. Server encrypts the packet with
858 session key shared between the server and the destination client,
859 and sends the packet to the client.
861 o Client 2. decrypts the packet.
864 Example: Private message from client to another client on different
865 servers. Clients has established secret shared private
866 message delivery key with each other and that is used in
867 the message encryption.
869 o Client 1. sends encrypted packet to its server. The packet is
870 encrypted with the private message delivery key shared between
873 o Server determines the destination of the packet and sends the
874 packet to the router.
876 o Router determines the destination of the packet and sends the
877 packet to the server.
879 o Server determines the client to which the packet is destined
880 to and sends the packet to the client.
882 o Client 2. decrypts the packet with the secret shared key.
885 If clients share secret key with each other the private message
886 delivery is much simpler since servers and routers between the
887 clients do not need to decrypt and re-encrypt the packet.
889 The process for clients on same server is much simpler as there are
890 no need to send the packet to the router. The process for clients
891 on different cells is same as above except that the packet is routed
892 outside the cell. The router of the destination cell routes the
893 packet to the destination same way as described above.
897 3.8.3 Client To Channel
899 Process of message delivery from client on channel to all the clients
902 Example: Channel of four users; two on same server, other two on
903 different cells. Client sends message to the channel.
905 o Client 1. encrypts the packet with channel key and sends the
906 packet to its server.
908 o Server determines local clients on the channel and sends the
909 packet to the Client on the same server. Server then sends
910 the packet to its router for further routing.
912 o Router determines local clients on the channel, if found
913 sends packet to the local clients. Router determines global
914 clients on the channel and sends the packet to its primary
915 router or fastest route.
917 o (Other router(s) do the same thing and sends the packet to
920 o Server determines local clients on the channel and sends the
921 packet to the client.
923 o All clients receiving the packet decrypts the packet.
927 3.8.4 Server To Server
929 Server to server packet delivery and encryption is described in above
930 examples. Router to router packet delivery is analogous to server to
931 server. However, some packets, such as channel packets, are processed
932 differently. These cases are described later in this document and
933 more in detail in [SILC2].
937 3.9 Key Exchange And Authentication
939 Key exchange is done always when for example client connects to server
940 but also when server and router and router and router connects to each
941 other. The purpose of key exchange protocol is to provide secure key
942 material to be used in the communication. The key material is used to
943 derive various security parameters used to secure SILC packets. The
944 SILC Key Exchange protocol is described in detail in [SILC3].
946 Authentication is done after key exchange protocol has been successfully
947 completed. The purpose of authentication is to authenticate for example
948 client connecting to the server. However, Usually clients are accepted
949 to connect to server without explicit authentication. Servers are
950 required use authentication protocol when connecting. The authentication
951 may be based on passphrase (pre-shared-secret) or public key. The
952 connection authentication protocol is described in detail in [SILC3].
958 This section defines all the allowed algorithms that can be used in
959 the SILC protocol. This includes mandatory cipher, mandatory public
960 key algorithm and MAC algorithms.
966 Cipher is the encryption algorithm that is used to protect the data
967 in the SILC packets. See [SILC2] of the actual encryption process and
968 definition of how it must be done. SILC has a mandatory algorithm that
969 must be supported in order to be compliant with this protocol.
971 Following ciphers are defined in SILC protocol:
974 blowfish-cbc Blowfish in CBC mode (mandatory)
975 twofish-cbc Twofish in CBC mode (optional)
976 rc6-cbc RC6 in CBC mode (optional)
977 rc5-cbc RC5 in CBC mode (optional)
978 mars-cbc Mars in CBC mode (optional)
979 none No encryption (optional)
983 All algorithms must use minimum of 128 bit key, by default. Several
984 algorithms, however, supports longer keys and it is recommended to use
985 longer keys if they are available.
987 Algorithm none does not perform any encryption process at all and
988 thus is not recommended to be used. It is recommended that no client
989 or server implementation would accept none algorithms except in special
992 Additional ciphers may be defined to be used in SILC by using the
993 same name format as above.
1001 3.10.2 Public Key Algorithms
1003 Public keys are used in SILC to authenticate entities in SILC network
1004 and to perform other tasks related to public key cryptography. The
1005 public keys are also used in the SILC Key Exchange protocol [SILC3].
1007 Following public key algorithms are defined in SILC protocol:
1014 Both of the algorithms are described in [Scheneir] and [Menezes].
1016 Additional public key algorithms may be defined to be used in SILC.
1020 3.10.3 MAC Algorithms
1022 Data integrity is protected by computing a message authentication code
1023 (MAC) of the packet data. See [SILC2] for details how to compute the
1026 Following MAC algorithms are defined in SILC protocol:
1029 hmac-sha1 HMAC-SHA1, length = 20 (mandatory)
1030 hmac-md5 HMAC-MD5, length = 16 (optional)
1031 none No MAC (optional)
1034 The none MAC is not recommended to be used as the packet is not
1035 authenticated when MAC is not computed. It is recommended that no
1036 client or server would accept none MAC except in special debugging
1039 The HMAC algorithm is described in [HMAC] and hash algorithms that
1040 are used as part of the HMACs are described in [Scheneir] and in
1043 Additional MAC algorithms may be defined to be used in SILC.
1047 3.10.4 Compression Algorithms
1049 SILC protocol supports compression that may be applied to unencrypted
1050 data. It is recommended to use compression on slow links as it may
1051 significantly speed up the data transmission. By default, SILC does not
1052 use compression which is the mode that must be supported by all SILC
1055 Following compression algorithms are defined:
1058 none No compression (mandatory)
1059 zlib GBU ZLIB (LZ77) compression (optional)
1062 Additional compression algorithms may be defined to be used in SILC.
1066 3.11 SILC Public Key
1068 This section defines the type and format of the SILC public key. All
1069 implementations must support this public key type. See [SILC3] for
1070 other optional public key and certificate types allowed in SILC
1071 protocol. Public keys in SILC may be used to authenticate entities
1072 and to perform other tasks related to public key cryptography.
1074 The format of the SILC Public Key is as follows:
1080 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
1081 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1082 | Public Key Length |
1083 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1084 | Algorithm Name Length | |
1085 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1089 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1090 | Identifier Length | |
1091 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
1095 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1099 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1103 Figure 4: SILC Public Key
1107 o Public Key Length (4 bytes) - Indicates the full length
1108 of the public key, not including this field.
1110 o Algorithm Name Length (2 bytes) - Indicates the length
1111 of the Algorithm Length field, not including this field.
1113 o Algorithm name (variable length) - Indicates the name
1114 of the public key algorithm that the key is. See the
1115 section 3.10.2 Public Key Algorithms for defined names.
1117 o Identifier Length (2 bytes) - Indicates the length of
1118 the Identifier field, not including this field.
1120 o Identifier (variable length) - Indicates the identifier
1121 of the public key. This data can be used to identify
1122 the owner of the key. The identifier is of following
1126 HN Host name or IP address
1133 Examples of an identifier:
1135 `UN=priikone, HN=poseidon.pspt.fi, E=priikone@poseidon.pspt.fi'
1137 `UN=sam, HN=dummy.fi, RN=Sammy Sam, O=Company XYZ, C=Finland'
1139 At least user name (UN) and host name (HN) must be provided as
1140 identifier. The fields are separated by commas (`,'). If
1141 comma is in the identifier string it must be written as `\\,',
1142 for example, `O=Company XYZ\\, Inc.'.
1144 o Public Data (variable length) - Includes the actual
1145 public data of the public key.
1147 The format of this field for RSA algorithm is
1156 The format of this field for DSS algorithm is
1168 The variable length fields are multiple precession
1169 integers encoded as strings in both examples.
1171 Other algorithms must define their own type of this
1172 field if they are used.
1175 All fields in the public key are in MSB (most significant byte first)
1182 This section describes various SILC procedures such as how the
1183 connections are created and registered, how channels are created and
1184 so on. The section describes the procedures only generally as details
1185 are described in [SILC2] and [SILC3].
1189 4.1 Creating Client Connection
1191 This section descibres the procedure when client connects to SILC server.
1192 When client connects to server the server must perform IP address lookup
1193 and reverse IP address lookup to assure that the origin host really is
1194 who it claims to be. Client, host, connecting to server must have
1195 both valid IP address and fully qualified domain name (FQDN).
1197 After that client and server performs SILC Key Exchange protocol which
1198 will provide the key material used later in the communication. The
1199 key exchange protocol must be completed successfully before the connection
1200 registration may continue. The SILC Key Exchange protocol is described
1203 Typical server implementation would keep a list of connections that it
1204 allows to connect to the server. The implementation would check, for
1205 example, the connecting client's IP address from the connection list
1206 before the SILC Key Exchange protocol has been started. Reason for
1207 this is that if the host is not allowed to connect to the server there
1208 is no reason to perform a key exchange protocol.
1210 After successful key exchange protocol the client and server performs
1211 connection authentication protocol. The purpose of the protocol is to
1212 authenticate the client connecting to the server. Flexible
1213 implementation could also accept the client to connect to the server
1214 without explicit authentication. However, if authentication is
1215 desired for a specific client it may be based on passphrase or
1216 public key authentication. If authentication fails the connection
1217 must be terminated. The connection authentication protocol is described
1220 After successful key exchange and authentication protocol the client
1221 registers itself by sending SILC_PACKET_NEW_CLIENT packet to the
1222 server. This packet includes various information about the client
1223 that the server uses to create the client. Server creates the client
1224 and sends SILC_PACKET_NEW_ID to the client which includes the created
1225 Client ID that the client must start using after that. After that
1226 all SILC packets from the client must have the Client ID as the
1227 Source ID in the SILC Packet Header, described in [SILC2].
1229 Client must also get the server's Server ID that is to be used as
1230 Destination ID in the SILC Packet Header when communicating with
1231 the server (for example when sending commands to the server). The
1232 ID may be resolved in two ways. Client can take the ID from an
1233 previously received packet from server that must include the ID,
1234 or to send SILC_COMMAND_INFO command and receive the Server ID as
1237 Server may choose not to use the information received in the
1238 SILC_PACKET_NEW_CLIENT packet. For example, if public key or
1239 certificate were used in the authentication, server may use those
1240 informations rather than what it received from client. This is suitable
1241 way to get the true information about client if it is available.
1243 The nickname of client is initially set to the username sent in the
1244 SILC_PACKET_NEW_CLIENT packet. User should set the nickname to more
1245 suitable by sending SILC_COMMAND_NICK command. However, this is not
1246 required as part of registration process.
1248 Server must also distribute the information about newly registered
1249 client to its router (or if the server is router, to all routers in
1250 the SILC network). More information about this in [SILC2].
1254 4.2 Creating Server Connection
1256 This section descibres the procedure when server connects to its
1257 router (or when router connects to other router, the cases are
1258 equivalent). The procedure is very much alike when client connects
1259 to the server thus it is not repeated here.
1261 One difference is that server must perform connection authentication
1262 protocol with proper authentication. Proper authentication is based
1263 on passphrase or public key authentication.
1265 After server and router has successfully performed the key exchange
1266 and connection authentication protocol, the server register itself
1267 to the router by sending SILC_PACKET_NEW_SERVER packet. This packet
1268 includes the server's Server ID that it has created by itself and
1269 other relevant information about the server.
1271 After router has received the SILC_PACKET_NEW_SERVER packet it
1272 distributes the information about newly registered server to all routers
1273 in the SILC network. More information about this in [SILC2].
1275 As client needed to resolve the destination ID this must be done by the
1276 server that connected to the router, as well. The way to resolve it is
1277 to get the ID from previously received packet. Server must also start
1278 using its own Server ID as Source ID in SILC Packet Header and the
1279 router's Server ID as Destination when communicating with the router.
1281 If the server has already connected clients and locally created
1282 channels the server must distribute these informations to the router.
1283 The distribution is done by sending packet SILC_PACKET_NEW_CHANNEL.
1284 See [SILC2] for more information on this.
1288 4.3 Joining to a Channel
1290 This section describes the procedure when client joins to a channel.
1291 Client may join to channel by sending command SILC_COMMAND_JOIN to the
1292 server. If the receiver receiving join command is normal server the
1293 server must check its local list whether this channel already exists
1294 locally. This would indicate that some client connected to the server
1295 has already joined to the channel. If this is case the client is
1296 joined to the client, new channel key is created and information about
1297 newly joined channel is sent to the router. The new channel key is
1298 also distributed to the router and to all clients on the channel.
1300 If the channel does not exist in the local list the command must be
1301 sent to the router which will then perform the actual joining
1302 procedure. When server receives the reply to the command from the
1303 router it must be distributed to the client who sent the command
1304 originally. Server will also receive the channel key from the server
1305 that it must distribute to the client who originally requested the
1306 join command. The server must also save the channel key.
1308 If the receiver of the join command is router it must first check its
1309 local list whether anyone in the cell has already joined to the channel.
1310 If this is the case the client is joined to the channel and reply is
1311 sent to the client. If the command was sent by server the command reply
1312 is sent to the server who sent it. Then the router must also create
1313 new channel key and distribute it to all clients on the channel and
1314 all servers that has clients on the channel.
1316 If the channel does not exist on the router's local list it must
1317 check the global list whether the channel exists at all. If it does
1318 the client is joined to the channel as described previously. If
1319 the channel does not exist the channel is created and the client
1320 is joined to the channel. The channel key is also created and
1321 distributed as previously described. The client joining to the created
1322 channel is made automatically channel founder and both channel founder
1323 and channel operator privileges is set for the client.
1325 When the router joins the client to the channel it must send
1326 information about newly joined client to all routers in the SILC
1327 network. Also, if the channel was created in the process, information
1328 about newly created channel must also be distributed to all routers.
1329 The distribution of newly created channel is done by sending packet
1330 SILC_PACKET_NEW_CHANNEL.
1332 It is important to note that new channel key is created always when
1333 new client joins to channel, whether the channel has existed previously
1334 or not. This way the new client on the channel is not able to decrypt
1335 any of the old traffic on the channel.
1337 Client who receives the reply to the join command must start using
1338 the received Channel ID in the channel message communication thereafter.
1339 However, client must not start communicating on the channel before
1340 it has received the packet SILC_PACKET_CHANNEL_KEY.
1342 If client wants to know the other clients currently on the channel
1343 the client must send SILC_COMMAND_NAMES command to receive a list of
1344 channel users. Server implementation, however, may send command reply
1345 packet to SILC_COMMAND_NAMES command after client has joined to the
1346 channel even if the client has not sent the command.
1350 4.4 Channel Key Generation
1352 Channel keys are created by router who creates the channel by taking
1353 enough randomness from cryptographically strong random number generator.
1354 The key is generated always when channel is created, when new client
1355 joins a channel and after the key has expired. Key could expire for
1358 The key must also be re-generated whenever some client leaves a channel.
1359 In this case the key is created from scratch by taking enough randomness
1360 from the random number generator. After that the key is distributed to
1361 all clients on the channel. However, channel keys are cell specific thus
1362 the key is created only on the cell where the client, who leaved the
1363 channel, exists. While the server or router is creating the new channel
1364 key, no other client may join to the channel. Messages that are sent
1365 while creating the new key are still processed with the old key. After
1366 server has sent the SILC_PACKET_CHANNEL_KEY packet must client start
1367 using the new key. If server creates the new key the server must also
1368 send the new key to its router. See [SILC2] on more information about
1369 how channel messages must be encrypted and decrypted when router is
1374 4.5 Private Message Sending and Reception
1376 Private messages are sent point to point. Client explicitly destines
1377 a private message to specific client that is delivered to only to that
1378 client. No other client may receive the private message. The receiver
1379 of the private message is destined in the SILC Packet Header as any
1380 other packet as well.
1382 If the sender of a private message does not know the receiver's Client
1383 ID, it must resolve it from server. There are two ways to resolve the
1384 client ID from server; it is recommended that client ipmlementations
1385 send SILC_COMMAND_IDENTIFY command to receive the Client ID. Client
1386 may also send SILC_COMMAND_WHOIS command to receive the Client ID.
1387 If the sender has received earlier a private message from the receiver
1388 it should have cached the Client ID from the SILC Packet Header.
1390 Receiver of a private message should not explicitly trust the nickname
1391 that it receives in the Private Message Payload, described in [SILC2].
1392 Implementations could resolve the nickname from server, as described
1393 previously, and compare the received Client ID and the SILC Packet
1394 Header's Client ID. The nickname in the payload is merely provided
1395 to be displayed for end user.
1397 See [SILC2] for describtion of private message encryption and decryption
1402 4.6 Private Message Key Generation
1404 Private message may be protected by key generated by client. The key
1405 may be generated and sent to the other client by sending packet
1406 SILC_PACKET_PRIVATE_MESSAGE_KEY which travels through the network
1407 and is secured by session keys. After that the private message key
1408 is used in the private message communication between those clients.
1409 See more information about how this works technically in [SILC2].
1411 Other choice is to entirely use keys that are not sent through
1412 the SILC network at all. This significantly adds security. This key
1413 would be pre-shared-key that is known by both of the clients. Both
1414 agree about using the key and starts sending packets that indicate
1415 that the private message is secured using private message key. This
1416 is the technical aspect mentioned previously that is described
1419 If the private message keys are not set to be used, which is the
1420 case by default in SILC, the private messages are secured by using
1421 normal session keys established by SILC Key Exchange protocol.
1425 4.7 Channel Message Sending and Reception
1427 Channel messages are delivered to group of users. The group forms a
1428 channel and all clients on the channel receives messages sent to the
1431 Channel messages are destined to channel by specifying the Channel ID
1432 as Destination ID in the SILC Packet Header. The server must then
1433 distribute the message to all clients on the channel by sending the
1434 channel message destined explicitly to a client on the channel.
1436 See [SILC2] for describtion of channel message encryption and decryption
1441 4.8 Session Key Regeneration
1443 Session keys should be regenerated peridiocally, say, once in an hour.
1444 The re-key process is started by sending SILC_PACKET_REKEY packet to
1445 other end, to indicate that re-key must be performed.
1447 If perfect forward secrecy (PFS) flag was selected in the SILC Key
1448 Exchange protocol [SILC3] the re-key must cause new key exchange with
1449 SKE protocol. In this case the protocol is secured with the old key
1450 and the protocol results to new key material. See [SILC3] for more
1451 information. After the SILC_PACKET_REKEY packet is sent the sender
1452 will perform the SKE protocol.
1454 If PFS flag was not set, which is the default case, then re-key is done
1455 without executing SKE protocol. In this case, the new key is created by
1456 hashing the old key with hash function selected earlier in the SKE
1457 protocol. If the digest length of the hash function is too short for the
1458 key, then the key is distributed as described in section Processing the
1459 Key Material in [SILC3]. After both parties has regenerated the session
1460 key, both send SILC_PACKET_REKEY_DONE packet to each other. These packets
1461 are still secured with the old key. After these packets, following
1462 packets must be protected with the new key.
1466 4.9 Command Sending and Reception
1468 Client usually sends the commands in the SILC network. In this case
1469 the client simply sends the command packet to server and the server
1470 processes it and replies with command reply packet.
1472 However, if the server is not able to process the command, it is usually
1473 sent to the server's router. This is case for example with commands such
1474 as, SILC_COMMAND_JOIN and SILC_COMMAND_WHOIS commands. However, there
1475 are other commands as well. For example, if client sends the WHOIS
1476 command requesting specific information about some client the server must
1477 send the WHOIS command to router so that all clients in SILC network
1478 are searched. The router, on the other hand, sends the WHOIS command
1479 to further to receive the exact information about the requested client.
1480 The WHOIS command travels all the way to the server who owns the client
1481 and it replies with command reply packet. Finally, the server who
1482 sent the command receives the command reply and it must be able to
1483 determine which client sent the original command. The server then
1484 sends command reply to the client. Implementations should have some
1485 kind of cache to handle, for example, WHOIS information. Servers
1486 and routers along the route could all cache the information for faster
1487 referencing in the future.
1489 The commands sent by server may be sent hop by hop until someone is able
1490 to process the command. However, it is preferred to destine the command
1491 as precisely as it is possible. In this case, other routers en route
1492 must route the command packet by checking the true sender and true
1493 destination of the packet. However, servers and routers must not route
1494 command reply packets to clients coming from other server. Client
1495 must not accept command reply packet originated from anyone else but
1496 from its own server.
1503 5.1 SILC Commands Syntax
1505 This section briefly describes the syntax of the command notions
1506 in this document. Every field in command is separated from each
1507 other by whitespaces (` ') indicating that each field is independent
1508 argument and each argument must have own Command Argument Payload.
1509 The number of maximum arguments are defined with each command
1510 separately. The Command Argument Payload is described in [SILC2].
1512 Every command defines specific number for each argument. Currently,
1513 they are defined in ascending order; first argument has number one
1514 (1), second has number two (2) and so on. This number is set into the
1515 Argument Type field in the Command Argument Payload. This makes it
1516 possible to send the arguments in free order as the number must be
1517 used to identify the type of the argument. This makes is it also
1518 possible to have multiple optional arguments in commands and in
1519 command replies. The number of argument is marked in parentheses
1520 before the actual argument.
1523 Example: Arguments: (1) <nickname> (2) <username@host>
1527 Every command replies with Status Payload. This payload tells the
1528 sender of the command whether the command was completed succefully or
1529 whether there was an error. If error occured the payload includes the
1530 error type. In the next section the Status Payload is not described
1531 as it is common to all commands and has been described here. Commands
1532 may reply with other arguments as well. These arguments are command
1533 specific and are described in the next section.
1542 Arguments: (1) <nickname>[@<server>] (2) <message>
1545 The command has maximum of 3 arguments. However, only first
1546 and second arguments are mandatory.
1548 First argument <nickname> is mandatory but may have optional
1549 <nickname@server> format as well. Second argument is mandatory
1550 <message> argument. Third argument is optional <count> argument.
1552 The numbers in parentheses are the argument specific numbers
1553 that specify the type of the argument in Command Argument Payload.
1554 The receiver always knows that, say, argument number two (2) is
1555 <message> argument, regardles of the ordering of the arguments in
1556 the Command Payload.
1562 Reply messages to the command:
1565 Arguments: (1) <Status Payload> (2) [<channel list>]
1566 (3) <idle time> (4) [<away message>]
1568 This command may reply with maximum of 4 arguments. However,
1569 only the first and third arguments are mandatory. The numbers
1570 in the parentheses have the same meaning as in the upper
1571 command sending specification.
1573 Every command reply with <Status Payload>, it is mandatory
1574 argument for all command replies and for this reason it is not
1575 described in the command reply descriptions.
1580 SILC_STATUS_ERR_TOO_MANY_TARGETS
1581 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1582 SILC_STATUS_ERR_NO_SUCH_NICK
1584 Every command reply also defines set of status message that it
1585 may return inside the <Status Payload>. All status messages
1586 are defined in the section 5.3 SILC Command Status Types.
1591 5.2 SILC Commands List
1593 This section lists all SILC commands, however, it is expected that a
1594 implementation and especially client implementation has many more
1595 commands that has only local affect. These commands are official
1596 SILC commands that has both client and server sides and cannot be
1597 characterized as local commands.
1599 List of all defined commands in SILC follows.
1604 None. This is reserved command and must not be sent.
1607 2 SILC_COMMAND_WHOIS
1610 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1612 Whois. Whois command is used to query various information about
1613 specific user. The user maybe requested by their nickname and
1614 server name. The query may find multiple matching users as
1615 there are no unique nicknames in the SILC. The <count> option
1616 maybe given to narrow down the number of accepted results. If
1617 this is not defined there are no limit of accepted results.
1618 The query may also be narrowed down by defining the server name
1621 To prevent miss-use of this service wildcards in the nickname
1622 or in the servername are not permitted. It is not allowed
1623 to request all users on some server. The WHOIS requests must
1624 be based on specific nickname request.
1626 The WHOIS request must be always forwarded to router by server
1627 so that all users are searched. However, the server still must
1628 search its locally connected clients. The server must send
1629 this command to the server who owns the requested client. That
1630 server must reply to the command.
1632 Reply messages to the command:
1635 Arguments: (1) <Status Payload> (2) <Client ID>
1636 (3) <nickname>[@<server>] (4) <username@host>
1637 (5) <real name> (6) [<channel list>]
1640 This command may reply with several command reply messages to
1641 form a list of results. In this case the status payload will
1642 include STATUS_LIST_START status in the first reply and
1643 STATUS_LIST_END in the last reply to indicate the end of the
1644 list. If there are only one reply the status is set to normal
1647 The command replies include the Client ID of the nickname,
1648 nickname and servername, username and hostnamea and users real
1649 name. Client should process these replies only after the last
1650 reply has been received with the STATUS_LIST_END status. If the
1651 <count> option were defined in the query there will be only
1652 <count> many replies from the server.
1657 SILC_STATUS_LIST_START
1658 SILC_STATUS_LIST_END
1659 SILC_STATUS_ERR_NO_SUCH_NICK
1660 SILC_STATUS_ERR_WILDCARDS
1661 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1662 SILC_STATUS_ERR_TOO_MANY_PARAMS
1665 3 SILC_COMMAND_WHOWAS
1668 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1670 Whowas. This command is used to query history information about
1671 specific user. The user maybe requested by their nickname and
1672 server name. The query may find multiple matching users as there
1673 are no unique nicknames in the SILC. The <count> option maybe
1674 given to narrow down the number of accepted results. If this
1675 is not defined there are no limit of accepted results. The query
1676 may also be narrowed down by defining the server name of the
1679 To prevent miss-use of this service wildcards in the nickname
1680 or in the servername are not permitted. The WHOWAS requests must
1681 be based on specific nickname request.
1683 The WHOWAS request must be always forwarded to router by server
1684 so that all users are searched. However, the server still must
1685 search its locally connected clients.
1687 Reply messages to the command:
1690 Arguments: (1) <Status Payload> (2) <nickname>[@<server>]
1693 This command may reply with several command reply messages to form
1694 a list of results. In this case the status payload will include
1695 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1696 the last reply to indicate the end of the list. If there are only
1697 one reply the status is set to normal STATUS_OK.
1699 The command replies with nickname and username and hostname.
1700 Every server must keep history for some period of time of its
1701 locally connected clients.
1706 SILC_STATUS_LIST_START
1707 SILC_STATUS_LIST_END
1708 SILC_STATUS_ERR_NO_SUCH_NICK
1709 SILC_STATUS_ERR_WILDCARDS
1710 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1711 SILC_STATUS_ERR_TOO_MANY_PARAMS
1714 4 SILC_COMMAND_IDENTIFY
1717 Arguments: (1) <nickname>[@<server>] (2) [<count>]
1719 Identify. Identify command is almost analogous to WHOIS command,
1720 except that it does not return as much information. Only relevant
1721 information such as Client ID is returned. This is usually used
1722 to get the Client ID of a client used in the communication with
1725 The query may find multiple matching users as there are no unique
1726 nicknames in the SILC. The <count> option maybe given to narrow
1727 down the number of accepted results. If this is not defined there
1728 are no limit of accepted results. The query may also be narrowed
1729 down by defining the server name of the nickname.
1731 To prevent miss-use of this service wildcards in the nickname
1732 or in the servername are not permitted. It is not allowed
1733 to request all users on some server. The IDENTIFY requests must
1734 be based on specific nickname request.
1736 Implementations may not want to give interface access to this
1737 commands as it is hardly a command that would be used a end user.
1738 However, it must be implemented as it is used with private message
1741 The IDENTIFY must be always forwarded to router by server so that
1742 all users are searched. However, server must still search its
1743 locally connected clients.
1745 Reply messages to the command:
1748 Arguments: (1) <Status Payload> (2) <Client ID>
1749 (3) [<nickname>[@<server>]] (4) [<username@host>]
1751 This command may reply with several command reply messages to form
1752 a list of results. In this case the status payload will include
1753 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1754 the last reply to indicate the end of the list. If there are only
1755 one reply the status is set to normal STATUS_OK.
1757 The command replies with Client ID of the nickname and if more
1758 information is available it may reply with nickname and username
1759 and hostname. If the <count> option were defined in the query
1760 there will be only <count> many replies from the server.
1765 SILC_STATUS_LIST_START
1766 SILC_STATUS_LIST_END
1767 SILC_STATUS_ERR_NO_SUCH_NICK
1768 SILC_STATUS_ERR_WILDCARDS
1769 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1770 SILC_STATUS_ERR_TOO_MANY_PARAMS
1776 Arguments: (1) <nickname>
1778 Set/change nickname. This command is used to set nickname for
1779 user. There is no limit of the length of the nickname in SILC.
1780 Nickname must not include any spaces (` '), non-printable
1781 characters, commas (`,') and any wildcard characters. Note:
1782 nicknames in SILC are case-sensitive which must be taken into
1783 account when searching clients by nickname.
1785 Reply messages to the command:
1788 Arguments: (1) <Status Payload> (2) <New ID Payload>
1790 This command is replied always with New ID Payload that is
1791 generated by the server every time user changes their nickname.
1792 Client receiving this payload must start using the received
1793 Client ID as its current valid Client ID. The New ID Payload
1794 is described in [SILC2].
1799 SILC_STATUS_ERR_WILDCARDS
1800 SILC_STATUS_ERR_NICKNAME_IN_USE
1801 SILC_STATUS_ERR_BAD_NICKNAME
1802 SILC_STATUS_ERR_NOT_REGISTERED
1803 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1804 SILC_STATUS_ERR_TOO_MANY_PARAMS
1810 Arguments: (1) [<Channel ID>] [<server>]
1812 The list command is used to list channels and their topics on
1813 current server. If the <Channel ID> parameter is used, only the
1814 status of that channel is displayed. Secret channels are not
1815 listed at all. Private channels are listed with status indicating
1816 that the channel is private.
1818 If the <server> argument is specified the specified server's
1819 channels are listed. In this case the command must be sent to
1820 the server who owns the channel that was requested.
1822 Reply messages to the command:
1825 Arguments: (1) <Status Payload> (2) <channel>
1828 This command may reply with several command reply messages to form
1829 a list of results. In this case the status payload will include
1830 STATUS_LIST_START status in the first reply and STATUS_LIST_END in
1831 the last reply to indicate the end of the list. If there are only
1832 one reply the status is set to normal STATUS_OK.
1834 This command replies with channel name and the topic of the
1835 channel. If the channel is private channel the <topic> includes
1841 SILC_STATUS_LIST_START
1842 SILC_STATUS_LIST_END
1843 SILC_STATUS_ERR_WILDCARDS
1844 SILC_STATUS_ERR_NOT_REGISTERED
1845 SILC_STATUS_ERR_TOO_MANY_PARAMS
1846 SILC_STATUS_ERR_NO_SUCH_CHANNEL
1847 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
1848 SILC_STATUS_ERR_NO_SUCH_SERVER
1856 7 SILC_COMMAND_TOPIC
1859 Arguments: (1) <Channel ID> (2) [<server>]]
1861 This command is used to change or view the topic of a channel.
1862 The topic for channel <Channel ID> is returned if there is no
1863 <topic> given. If the <topic> parameter is present, the topic
1864 for that channel will be changed, if the channel modes permit
1867 Reply messages to the command:
1870 Arguments: (1) <Status Payload> (2) [<topic>]
1872 The command may reply with the topic of the channel if it is
1878 SILC_STATUS_ERR_NOT_ON_CHANNEL
1879 SILC_STATUS_ERR_WILDCARDS
1880 SILC_STATUS_ERR_NOT_REGISTERED
1881 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1882 SILC_STATUS_ERR_NO_SUCH_CHANNEL
1883 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
1884 SILC_STATUS_ERR_NO_CHANNEL_ID
1885 SILC_STATUS_ERR_BAD_CHANNEL_ID
1886 SILC_STATUS_ERR_TOO_MANY_PARAMS
1887 SILC_STATUS_ERR_NO_CHANNEL_PRIV
1890 8 SILC_COMMAND_INVITE
1893 Arguments: (1) <Client ID> (2) <channel>
1895 This command is used to invite other clients to join to the
1896 channel. There is no requirement that the channel the target
1897 client is being invited to must exist or be a valid channel.
1898 The <Client ID> argument is the target client's ID that is being
1901 Reply messages to the command:
1905 Arguments: (1) <Status Payload>
1907 This command replies only with Status Payload.
1912 SILC_STATUS_ERR_NOT_ON_CHANNEL
1913 SILC_STATUS_ERR_WILDCARDS
1914 SILC_STATUS_ERR_NOT_REGISTERED
1915 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1916 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
1917 SILC_STATUS_ERR_TOO_MANY_PARAMS
1918 SILC_STATUS_ERR_NO_RECIPIENT
1919 SILC_STATUS_ERR_USER_ON_CHANNEL
1920 SILC_STATUS_ERR_NO_CLIENT_ID
1926 Arguments: (1) [<quit message>]
1928 This command is used by client to end SILC session. The server
1929 must close the connection to a client which sends this command.
1930 if <quit message> is given it will be sent to other clients on
1931 channel if the client is on channel when quitting.
1933 Reply messages to the command:
1935 This command does not reply anything.
1938 10 SILC_COMMAND_KILL
1941 Arguments: (1) <Client ID> (2) [<comment>]
1943 This command is used by SILC operators to remove a client from
1944 SILC network. The removing has temporary effects and client may
1945 reconnect to SILC network. The <Client ID> is the client to be
1946 removed from SILC. The <comment> argument may be provided to
1947 give to the removed client some information why it was removed
1950 Reply messages to the command:
1953 Arguments: (1) <Status Payload>
1955 This command replies only with Status Payload.
1960 SILC_STATUS_ERR_WILDCARDS
1961 SILC_STATUS_ERR_NOT_REGISTERED
1962 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
1963 SILC_STATUS_ERR_TOO_MANY_PARAMS
1964 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
1965 SILC_STATUS_ERR_NO_CLIENT_ID
1968 11 SILC_COMMAND_INFO
1971 Arguments: (1) [<server>]
1973 This command is used to fetch various information about a server.
1974 If <server> argument is specified the command must be sent to
1975 the requested server.
1977 Reply messages to the command:
1980 Arguments: (1) <Status Payload> (2) <Server ID>
1983 This command replies with the Server ID of the server and a
1984 string which tells the information about the server.
1989 SILC_STATUS_ERR_WILDCARDS
1990 SILC_STATUS_ERR_NOT_REGISTERED
1991 SILC_STATUS_ERR_TOO_MANY_PARAMS
1992 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
1993 SILC_STATUS_ERR_NO_SUCH_SERVER
2000 12 SILC_COMMAND_CONNECT
2003 Arguments: (1) <Server ID>
2004 (2) [<remote server/router>[:<port>]]
2006 This command is used by operators to force a server to try to
2007 establish a new connection to another router (if the connecting
2008 server is normal server) or server (if the conneceting server is
2009 router server). Operator may specify the server/router to be
2010 connected by setting <remote server> argument.
2012 Reply messages to the command:
2015 Arguments: (1) <Status Payload>
2017 This command replies only with Status Payload.
2022 SILC_STATUS_ERR_WILDCARDS
2023 SILC_STATUS_ERR_NOT_REGISTERED
2024 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2025 SILC_STATUS_ERR_TOO_MANY_PARAMS
2026 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2027 SILC_STATUS_ERR_NO_SERVER_PRIV
2028 SILC_STATUS_ERR_NO_ROUTER_PRIV
2031 13 SILC_COMMAND_PING
2034 Arguments: (1) <Server ID>
2036 This command is used by clients to test the communication
2037 channel to its server if client suspects that the communication
2038 is not working correctly. The <Server ID> is the ID of the
2039 server the client is connected to.
2041 Reply messages to the command:
2044 Arguments: (1) <Status Payload>
2046 This command replies only with Status Payload. Server returns
2047 SILC_STATUS_OK in Status Payload if pinging was successful.
2052 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2053 SILC_STATUS_ERR_TOO_MANY_PARAMS
2054 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2055 SILC_STATUS_ERR_NOT_REGISTERED
2058 14 SILC_COMMAND_OPER
2061 Arguments: (1) <username> (2) <authentication data>
2063 This command is used by normal client to obtain server operator
2064 privileges on some server or router. Note that router operator
2065 has router privileges that supersedes the server operator
2066 privileges and this does not obtain those privileges. Client
2067 must use SILCOPER command to obtain router level privileges.
2069 The <username> is the username set in the server configurations
2070 as operator. The <authentication data> is the data that the
2071 client is authenticated against. It may be passphrase prompted
2072 for user on client's screen or it may be public key
2073 authentication data (data signed with private key), or
2076 Reply messages to the command:
2079 Arguments: (1) <Status Payload>
2081 This command replies only with Status Payload.
2086 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2087 SILC_STATUS_ERR_TOO_MANY_PARAMS
2088 SILC_STATUS_ERR_NOT_REGISTERED
2089 SILC_STATUS_ERR_BAD_PASSWORD
2090 SILC_STATUS_ERR_AUTH_FAILED
2098 15 SILC_COMMAND_JOIN
2101 Arguments: (1) <channel> (2) [<passphrase>]
2104 Join to channel/create new channel. This command is used to
2105 join to a channel. If the channel does not exist the channel is
2106 created on the server receiving the join request. The channel
2107 may be protected with passphrase. If this is the case the
2108 passphrase must be sent along the join command.
2110 The name of the <channel> must not include any spaces (` '),
2111 non-printable characters, commas (`,') or any wildcard characters.
2113 Cipher to be used to secure the traffic on the channel may be
2114 requested by sending the name of the requested <cipher>. This
2115 is used only if the channel does not exist and is created. If
2116 the channel already exists the cipher set previously for the
2117 channel will be used to secure the traffic.
2119 The server must check whether the user is allowed to join to
2120 the requested channel. Various modes set to the channel affect
2121 the ability of the user to join the channel. These conditions
2124 o The user must be invited to the channel if the channel
2125 is invite-only channel.
2127 o The Client ID/nickname/username/hostname must not match
2130 o The correct passphrase must be provided if passphrase
2131 is set to the channel.
2133 o The user count limit, if set, must not be reached.
2135 Reply messages to the command:
2138 Arguments: (1) <Status Payload> (2) <channel>
2139 (3) <Channel ID> (4) <channel mode mask>
2142 This command replies with the channel name requested by the
2143 client, channel ID of the channel and topic of the channel
2144 if it exists. It also replies with the channel mode mask
2145 which tells all the modes set on the channel. If the
2146 channel is created the mode mask is zero (0).
2148 Client must not start transmitting to the channel even after
2149 server has replied to this command. Client is permitted to
2150 start transmitting on channel after server has sent packet
2151 SILC_PACKET_CHANNEL_KEY to the client.
2156 SILC_STATUS_ERR_WILDCARDS
2157 SILC_STATUS_ERR_NOT_REGISTERED
2158 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2159 SILC_STATUS_ERR_TOO_MANY_PARAMS
2160 SILC_STATUS_ERR_BAD_PASSWORD
2161 SILC_STATUS_ERR_CHANNEL_IS_FULL
2162 SILC_STATUS_ERR_NOT_INVITED
2163 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
2164 SILC_STATUS_ERR_BAD_CHANNEL
2165 SILC_STATUS_ERR_USER_ON_CHANNEL
2168 16 SILC_COMMAND_MOTD
2171 Arguments: (1) <server>
2173 This command is used to query the Message of the Day of a server.
2175 Reply messages to the command:
2178 Arguments: (1) <Status Payload> (2) [<motd>]
2180 This command replies with the motd message if it exists.
2185 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2186 SILC_STATUS_ERR_TOO_MANY_PARAMS
2187 SILC_STATUS_ERR_NOT_REGISTERED
2188 SILC_STATUS_ERR_NO_SUCH_SERVER
2195 17 SILC_COMMAND_UMODE
2198 Arguments: (1) <Client ID> (2) <client mode mask>
2200 This command is used by client to set/unset modes for itself.
2201 However, there are some modes that the client may not set itself,
2202 but they will be set by server. However, client may unset any
2203 mode. Modes may be masked together ORing them thus having
2204 several modes set. Client must keep its client mode mask
2205 locally so that the mode setting/unsetting would work without
2206 problems. Client may change only its own modes.
2208 Following client modes are defined:
2210 0x0000 SILC_UMODE_NONE
2212 No specific mode for client. This is the initial
2213 setting when new client is created. The client is
2217 0x0001 SILC_UMODE_SERVER_OPERATOR
2219 Marks the user as server operator. Client cannot
2220 set this mode itself. Server sets this mode to the
2221 client when client attains the server operator
2222 privileges by SILC_COMMAND_OPER command. Client
2223 may unset the mode itself.
2226 0x0002 SILC_UMODE_ROUTER_OPERATOR
2228 Marks the user as router (SILC) operator. Client
2229 cannot this mode itself. Router sets this mode to
2230 the client when client attains the router operator
2231 privileges by SILC_COMMAND_SILCOPER command. Client
2232 may unset the mode itself.
2234 Reply messages to the command:
2237 Arguments: (1) <Status Payload> (2) <client mode mask>
2239 This command replies with the changed client mode mask that
2240 the client is required to keep locally.
2246 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2247 SILC_STATUS_ERR_TOO_MANY_PARAMS
2248 SILC_STATUS_ERR_NOT_REGISTERED
2249 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2250 SILC_STATUS_ERR_BAD_CLIENT_ID
2251 SILC_STATUS_ERR_NOT_YOU
2252 SILC_STATUS_ERR_UNKNOWN_MODE
2253 SILC_STATUS_ERR_NO_RECIPIENT
2254 SILC_STATUS_ERR_NO_CLIENT_ID
2257 18 SILC_COMMAND_CMODE
2260 Arguments: (1) <Channel ID> (2) <channel mode mask>
2261 (3) [<user limit>] (4) [<passphrase>]
2262 (5) [<Client ID>] (6) [<cipher>[:<key len>]]
2264 This command is used by client to set or change channel flags on
2265 a channel. Channel has several modes that set various properties
2266 of a channel. Modes may be masked together by ORing them thus
2267 having several modes set. The <Channel ID> is the ID of the
2268 target channel. The client changing channel mode must be on
2269 the same channel and poses sufficient privileges to be able to
2272 Following channel modes are defined:
2274 0x0000 SILC_CMODE_NONE
2276 No specific mode on channel. This is the default when
2277 channel is created. This means that channel is just plain
2281 0x0001 SILC_CMODE_PRIVATE
2283 Channel is private channel. Private channels are shown
2284 in the channel list listed with SILC_COMMAND_LIST command
2285 with indicatioin that the channel is private. Also,
2286 client on private channel will no be detected to be on
2287 the channel as the channel is not shown in the client's
2288 currently joined channel list. Channel founder and
2289 channel operator may set/unset this mode.
2291 Typical implementation would use [+|-]p on user interface
2292 to set/unset this mode.
2295 0x0002 SILC_CMODE_SECRET
2297 Channel is secret channel. Secret channels are not shown
2298 in the list listed with SILC_COMMAND_LIST command. Secret
2299 channels can be considered to be invisible channels.
2300 Channel founder and channel operator may set/unset this
2303 Typical implementation would use [+|-]s on user interface
2304 to set/unset this mode.
2307 0x0004 SILC_CMODE_PRIVKEY
2309 Channel uses private channel key to protect the traffic
2310 on the channel. When this mode is set the client will be
2311 responsible to set the key it wants to use to encrypt and
2312 decrypt the traffic on channel. Server generated channel
2313 keys are not used at all. This mode provides additional
2314 security as clients on channel may agree to use private
2315 channel key that even servers do not know. Naturally,
2316 this requires that every client on the channel knows
2317 the key before hand (it is considered to be pre-shared-
2318 key). This specification does not define how the private
2319 channel key is set as it is entirely local setting on
2322 As it is local setting it is possible to have several
2323 private channel keys on one channel. In this case several
2324 clients can talk on same channel but only those clients
2325 that share the key with the message sender will be able
2326 to hear the talking. Client should not display those
2327 message for the end user that it is not able to decrypt
2328 when this mode is set.
2330 Only channel founder may set/unset this mode. If this
2331 mode is unset the server will distribute new channel
2332 key to all clients on the channel which will be used
2335 Typical implementation would use [+|-]k on user interface
2336 to set/unset this mode.
2339 0x0008 SILC_CMODE_INVITE
2341 Channel is invite only channel. Client may join to this
2342 channel only if it is invited to the channel. Channel
2343 founder and channel operator may set/unset this mode.
2345 Typical implementation would use [+|-]i on user interface
2346 to set/unset this mode.
2349 0x0010 SILC_CMODE_TOPIC
2351 The topic of the channel may only be set by client that
2352 is channel founder or channel operator. Normal clients
2353 on channel will not be able to set topic when this mode
2354 is set. Channel founder and channel operator may set/
2357 Typical implementation would use [+|-]t on user interface
2358 to set/unset this mode.
2361 0x0020 SILC_CMODE_ULIMIT
2363 User limit has been set to the channel. New clients
2364 may not join to the channel when the limit set is
2365 reached. Channel founder and channel operator may set/
2366 unset the limit. The <user limit> argument is the
2367 number of limited users.
2369 Typical implementation would use [+|-]l on user interface
2370 to set/unset this mode.
2373 0x0040 SILC_CMODE_PASSPHRASE
2375 Passphrase has been set to the channel. Client may
2376 join to the channel only if it is able to provide the
2377 correct passphrase. Setting passphrases to channel
2378 is entirely safe as all commands are protected in the
2379 SILC network. Only channel founder may set/unset
2380 the passphrase. The <passphrase> argument is the
2383 Typical implementation would use [+|-]a on user interface
2384 to set/unset this mode.
2387 0x0080 SILC_CMODE_BAN
2389 Ban mask has been set to the channel. The ban mask
2390 may be used to ban specific clients to join the channel.
2391 The <ban mask> argument is the set ban mask. When
2392 unsetting a ban mask the mask must be provided as
2393 argument. Channel founder and channel operator may
2394 set/unset this mode. Channel founder may not be
2395 added to the ban list.
2397 Typical implementation would use [+|-]b on user interface
2398 to set/unset this mode.
2401 0x0100 SILC_CMODE_OPERATOR
2403 Sets channel operator privileges on the channel for a
2404 client on the channel. The <Client ID> argument is the
2405 target client on the channel. Channel founder and
2406 channel operator may set/unset (promote/demote) this
2409 Typical implementation would use [+|-]o on user interface
2410 to set/unset this mode.
2413 0x0200 SILC_CMODE_CIPHER
2415 Sets specific cipher to be used to protect channel
2416 traffic. The <cipher> argument is the requested cipher.
2417 When set or unset the server must re-generate new
2418 channel key. If <key len> argument is specified with
2419 <cipher> argument the new key is generated of <key len>
2422 Typical implementation would use [+|-]c on user interface
2423 to set/unset this mode.
2426 To make the mode system work, client must keep the channel mode
2427 mask locally so that the mode setting and unsetting would work
2428 without problems. The client receives the initial channel mode
2429 mask when it joins to the channel. When the mode changes on
2430 channel the server distributes the changed channel mode mask to
2431 all clients on the channel by sending SILC_COMMAND_CMODE command
2435 Reply messages to the command:
2438 Arguments: (1) <Status Payload> (2) <channel mode mask>
2440 This command replies with the changed channel mode mask that
2441 client is required to keep locally. The same mask is also
2442 sent to all clients on channel by sending additional command
2448 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2449 SILC_STATUS_ERR_TOO_MANY_PARAMS
2450 SILC_STATUS_ERR_NOT_REGISTERED
2451 SILC_STATUS_ERR_NOT_ON_CHANNEL
2452 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2453 SILC_STATUS_ERR_BAD_CHANNEL_ID
2454 SILC_STATUS_ERR_NO_CHANNEL_ID
2455 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2456 SILC_STATUS_ERR_UNKNOWN_MODE
2457 SILC_STATUS_ERR_NO_CLIENT_ID
2460 19 SILC_COMMAND_KICK
2463 Arguments: (1) <channel> (2) <Client ID>
2466 This command is used by channel operators to remove a client from
2467 channel. The <channel> argument is the channel the client to be
2468 removed is on currently. Note that the "kicker" must be on the same
2469 channel. If <comment> is provided it will be sent to the removed
2472 Reply messages to the command:
2475 Arguments: (1) <Status Payload>
2477 This command replies only with Status Payload.
2482 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2483 SILC_STATUS_ERR_TOO_MANY_PARAMS
2484 SILC_STATUS_ERR_NOT_REGISTERED
2485 SILC_STATUS_ERR_NO_SUCH_CHANNEL
2486 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2487 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2488 SILC_STATUS_ERR_NO_CLIENT_ID
2491 20 SILC_COMMAND_RESTART
2496 This command may only be used by server operator to force a
2497 server to restart itself.
2499 Reply messages to the command:
2502 Arguments: (1) <Status Payload>
2504 This command replies only with Status Payload.
2509 SILC_STATUS_ERR_NOT_REGISTERED
2510 SILC_STATUS_ERR_NO_SERVER_PRIV
2513 21 SILC_COMMAND_CLOSE
2516 Arguments: (1) <Server ID>
2518 This command is used only by operator to close connection to a
2519 remote site. The <Server ID> argument is the ID of the remote
2520 site and must be valid.
2522 Reply messages to the command:
2525 Arguments: (1) <Status Payload>
2527 This command replies only with Status Payload.
2534 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2535 SILC_STATUS_ERR_TOO_MANY_PARAMS
2536 SILC_STATUS_ERR_NOT_REGISTERED
2537 SILC_STATUS_ERR_NO_SUCH_SERVER
2538 SILC_STATUS_ERR_NO_SERVER_PRIV
2539 SILC_STATUS_ERR_NO_SUCH_SERVER_ID
2547 This command is used only by operator to shutdown the server.
2548 All connections to the server will be closed and the server is
2551 Reply messages to the command:
2554 Arguments: (1) <Status Payload>
2556 This command replies only with Status Payload.
2561 SILC_STATUS_ERR_NOT_REGISTERED
2562 SILC_STATUS_ERR_NO_SERVER_PRIV
2565 23 SILC_COMMAND_SILCOPER
2568 Arguments: (1) <username> (2) <authentication data>
2570 This command is used by normal client to obtain router operator
2571 privileges (also known as SILC operator) on some router. Note
2572 that router operator has router privileges that supersedes the
2573 server operator privileges.
2575 The <username> is the username set in the server configurations
2576 as operator. The <authentication data> is the data that the
2577 client is authenticated against. It may be passphrase prompted
2578 for user on client's screen or it may be public key
2579 authentication data (data signed with private key), or
2582 Difference between router operator and server operator is that
2583 router operator is able to handle cell level properties while
2584 server operator (even on router server) is able to handle only
2585 local properties, such as, local connections and normal server
2588 Reply messages to the command:
2591 Arguments: (1) <Status Payload>
2593 This command replies only with Status Payload.
2598 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2599 SILC_STATUS_ERR_TOO_MANY_PARAMS
2600 SILC_STATUS_ERR_NOT_REGISTERED
2601 SILC_STATUS_ERR_BAD_PASSWORD
2602 SILC_STATUS_ERR_AUTH_FAILED
2605 24 SILC_COMMAND_LEAVE
2608 Arguments: (1) <Channel ID>
2610 This command is used by client to leave a channel the client is
2611 joined to. After a client has leaved the channel the server
2612 must create new key for the channel and distribute to all clients
2613 still currently on the channel.
2615 Reply messages to the command:
2618 Arguments: (1) <Status Payload>
2620 This command replies only with Status Payload.
2625 SILC_STATUS_ERR_NOT_REGISTERED
2626 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2627 SILC_STATUS_ERR_TOO_MANY_PARAMS
2628 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2629 SILC_STATUS_ERR_BAD_CHANNEL_ID
2630 SILC_STATUS_ERR_NO_CHANNEL_ID
2633 25 SILC_COMMAND_NAMES
2636 Arguments: (1) <Channel ID>
2638 This command is used to list user names currently on the requested
2639 channel; argument <Channel ID>. The server must resolve the
2640 user names and send a comma (`,') separated list of user names
2641 on the channel. Server or router may resolve the names by sending
2642 SILC_COMMAND_WHOIS commands.
2644 If the requested channel is a private or secret channel, this
2645 command must not send the list of users, as private and secret
2646 channels cannot be seen by outside. In this case the returned
2647 name list may include a indication that the server could not
2648 resolve the names of the users on the channel.
2650 Reply messages to the command:
2653 Arguments: (1) <Status Payload> (2) <name list>
2655 This command replies with the comma separated list of users on
2661 SILC_STATUS_ERR_NOT_REGISTERED
2662 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2663 SILC_STATUS_ERR_TOO_MANY_PARAMS
2664 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2665 SILC_STATUS_ERR_BAD_CHANNEL_ID
2666 SILC_STATUS_ERR_NO_CHANNEL_ID
2667 SILC_STATUS_ERR_NOT_ON_CHANNEL
2672 Currently undefined commands.
2675 255 SILC_COMMAND_MAX
2677 Reserved command. This must not be sent.
2682 5.3 SILC Command Status Types
2685 5.3.1 SILC Command Status Payload
2687 Command Status Payload is sent in command reply messages to indicate
2688 the status of the command. The payload is one of argument in the
2689 command thus this is the data area in Command Argument Payload described
2690 in [SILC2]. The payload is only 2 bytes of length. Following diagram
2691 represents the Command Status Payload (field is always in MSB order).
2697 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
2698 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2700 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2704 Figure 5: SILC Command Status Payload
2708 o Status Message (2 bytes) - Indicates the status message.
2709 All Status messages are described in the next section.
2714 5.3.2 SILC Command Status List
2716 Command Status messages are returned in the command reply messages
2717 to indicate whether the command were executed without errors. If error
2718 has occured the status tells which error occured. Status payload only
2719 sends numeric reply about the status. Receiver of the payload must
2720 convert the numeric values into human readable error messages. The
2721 list of status messages below has an example human readable error
2722 messages that client may display for the user.
2724 List of all defined command status messages following.
2727 Generic status messages:
2731 Ok status. Everything went Ok. The status payload maybe
2732 safely ignored in this case.
2734 1 SILC_STATUS_LIST_START
2736 Start of the list. There will be several command replies and
2737 this reply is the start of the list.
2739 2 SILC_STATUS_LIST_END
2741 End of the list. There were several command replies and this
2742 reply is the last of the list. There won't be other replies
2743 beloning to this list after this one.
2747 Currently undefined and has been reserved for the future.
2750 Error status message:
2752 10 SILC_STATUS_ERR_NO_SUCH_NICK
2754 "No such nickname". Requested nickname does not exist.
2756 11 SILC_STATUS_ERR_NO_SUCH_CHANNEL
2758 "No such channel". Requested channel name does not exist.
2760 12 SILC_STATUS_ERR_NO_SUCH_SERVER
2762 "No such server". Requested server name does not exist.
2764 13 SILC_STATUS_ERR_TOO_MANY_TARGETS
2766 "Duplicate recipients. No message delivered". Message were
2767 tried to be sent to recipient which has several occurrences in
2770 14 SILC_STATUS_ERR_NO_RECIPIENT
2772 "No recipient given". Command required recipient which was
2775 15 SILC_STATUS_ERR_UNKNOWN_COMMAND
2777 "Unknown command". Command sent to server is unknown by the
2782 16 SILC_STATUS_ERR_WILDCARDS
2784 "Wildcards cannot be used". Wildcards were provided but they
2787 17 SILC_STATUS_ERR_NO_CLIENT_ID
2789 "No Client ID given". Client ID were expected as command
2790 parameter but were not found.
2792 18 SILC_STATUS_ERR_NO_CHANNEL_ID
2794 "No Channel ID given". Channel ID were expected as command
2795 parameter but were not found.
2797 19 SILC_STATUS_ERR_BAD_CLIENT_ID
2799 "Bad Client ID". Client ID provided were erroneous.
2801 20 SILC_STATUS_ERR_BAD_CHANNEL_ID
2803 "Bad Channel ID". Channel ID provided were erroneous.
2805 21 SILC_STATUS_ERR_NO_SUCH_CLIENT_ID
2807 "No such Client ID". Client ID provided does not exist.
2810 22 SILC_STATUS_ERR_NO_SUCH_CHANNEL_ID
2812 "No such Channel ID". Channel ID provided does not exist.
2814 23 SILC_STATUS_ERR_NICKNAME_IN_USE
2816 "Nickname already exists". Nickname created could not be
2817 registered because number of same nicknames were already set to
2818 maximum. This is not expected to happen in real life but is
2821 24 SILC_STATUS_ERR_NOT_ON_CHANNEL
2823 "You are not on that channel". The command were specified for
2824 client user is not currently on.
2826 25 SILC_STATUS_ERR_USER_ON_CHANNEL
2828 "User already on channel". User were invited on channel they
2831 26 SILC_STATUS_ERR_NOT_REGISTERED
2833 "You have not registered". User executed command that requires
2834 the client to be registered on the server before it may be
2837 27 SILC_STATUS_ERR_NOT_ENOUGH_PARAMS
2839 "Not enough parameters". Command requires more parameters
2842 28 SILC_STATUS_ERR_TOO_MANY_PARAMS
2844 "Too many parameters". Too many parameters were provided
2847 29 SILC_STATUS_ERR_PERM_DENIED
2849 "Your host is not among the privileged". The client tried to
2850 register on server that does not allow this host to connect.
2852 30 SILC_STATUS_ERR_BANNED_FROM_SERVER
2854 "You are banned from this server". The client tried to register
2855 on server that has explicitly denied this host to connect.
2857 31 SILC_STATUS_ERR_BAD_PASSWORD
2859 "Cannot join channel. Incorrect password". Password provided for
2860 channel were not accepted.
2862 32 SILC_STATUS_ERR_CHANNEL_IS_FULL
2864 "Cannot join channel. Channel is full". The channel is full
2865 and client cannot be joined to it.
2867 33 SILC_STATUS_ERR_NOT_INVITED
2869 "Cannot join channel. You have not been invited". The channel
2870 is invite only channel and client has not been invited.
2872 34 SILC_STATUS_ERR_BANNED_FROM_CHANNEL
2874 "Cannot join channel. You have been banned". The client has
2875 been banned from the channel.
2879 35 SILC_STATUS_ERR_UNKNOWN_MODE
2881 "Unknown mode". Mode provided by the client were unknown to
2884 36 SILC_STATUS_ERR_NOT_YOU
2886 "Cannot change mode for other users". User tried to change
2887 someone else's mode.
2889 37 SILC_STATUS_ERR_NO_CHANNEL_PRIV
2891 "Permission denied. You are not channel operator". Command may
2892 be executed only by channel operator.
2894 38 SILC_STATUS_ERR_NO_SERVER_PRIV
2896 "Permission denied. You are not server operator". Command may
2897 be executed only by server operator.
2899 39 SILC_STATUS_ERR_NO_ROUTER_PRIV
2901 "Permission denied. You are not SILC operator". Command may be
2902 executed only by router (SILC) operator.
2904 40 SILC_STATUS_ERR_BAD_NICKNAME
2906 "Bad nickname". Nickname requested contained illegal characters
2909 41 SILC_STATUS_ERR_BAD_CHANNEL
2911 "Bad channel name". Channel requested contained illegal characters
2914 42 SILC_STATUS_ERR_AUTH_FAILED
2916 "Authentication failed". The authentication data sent as
2917 argument were wrong and thus authentication failed.
2922 6 Security Considerations
2924 Security is central to the design of this protocol, and these security
2925 considerations permeate the specification.
2934 [SILC2] Riikonen, P., "SILC Packet Protocol", Internet Draft,
2937 [SILC3] Riikonen, P., "SILC Key Exchange and Authentication
2938 Protocols", Internet Draft, June 2000.
2940 [IRC] Oikarinen, J., and Reed D., "Internet Relay Chat Protocol",
2943 [SSH-TRANS] Ylonen, T., et al, "SSH Transport Layer Protocol",
2946 [PGP] Callas, J., et al, "OpenPGP Message Format", RFC 2440,
2949 [SPKI] Ellison C., et al, "SPKI Certificate Theory", RFC 2693,
2952 [PKIX-Part1] Housley, R., et al, "Internet X.509 Public Key
2953 Infrastructure, Certificate and CRL Profile", RFC 2459,
2956 [Schneier] Schneier, B., "Applied Cryptography Second Edition",
2957 John Wiley & Sons, New York, NY, 1996.
2959 [Menezes] Menezes, A., et al, "Handbook of Applied Cryptography",
2962 [OAKLEY] Orman, H., "The OAKLEY Key Determination Protocol",
2963 RFC 2412, November 1998.
2965 [ISAKMP] Maughan D., et al, "Internet Security Association and
2966 Key Management Protocol (ISAKMP)", RFC 2408, November
2969 [IKE] Harkins D., and Carrel D., "The Internet Key Exhange
2970 (IKE)", RFC 2409, November 1998.
2972 [HMAC] Krawczyk, H., "HMAC: Keyed-Hashing for Message
2973 Authentication", RFC 2104, February 1997.
2990 EMail: priikone@poseidon.pspt.fi